The Action of Unsaturated Compounds on Natural Rubber in Solution. II. The Reaction Induced by Heat Alone

1952 ◽  
Vol 25 (2) ◽  
pp. 275-286
Author(s):  
André Delalande
Keyword(s):  
Free Radicals ◽  
Elevated Temperature ◽  
Natural Rubber ◽  
Addition Reaction ◽  
Thermal Reaction ◽  
Temperature Range ◽  
Unsaturated Compounds ◽  
Mechanism Of The Reaction

Abstract The addition reaction at an elevated temperature (170° C) of maleic N-methylimide with natural rubber in solution was studied. Attempts were made to apply the principles of kinetics to this thermal reaction with a view to understanding the nature of the reaction, but the complexity of the system made impossible any chance of attaining the results hoped for. A comparison of the fixation of acrylonitrile and that of maleic N-methylimide in the temperature range of 160°–200° C showed that the rates of these two reactions are in the ratio of 1 to 25–30. A determination of the unsaturation of the addition products showed that fixation is on the α-methylenic carbon atoms of the rubber hydrocarbon. Finally a mechanism of the reaction is proposed, in which free radicals play a part.

The Action of Unsaturated Compounds on Natural Rubber in Solution. I. The Reaction Catalyzed by a Peroxide

1952 ◽  
Vol 25 (1) ◽  
pp. 74-88
Author(s):  
André Delalande
Keyword(s):  
Experimental Study ◽  
Natural Rubber ◽  
Thermal Reaction ◽  
Unsaturated Compounds ◽  
Simultaneous Use ◽  
Short Time ◽  
Insight Into

Abstract It has been shown that, by the simultaneous use of maleic N-methylimide and p-bromobenzoyl peroxide, it is possible to gain an insight into the fixation of ethylene compounds to rubber in solution. The investigation has made it clear that the presence of a peroxide is not indispensable, since the reaction continues even after the peroxide is completely decomposed, although at a much slower rate. Furthermore, by raising the temperature, it is possible to fix maleic N-methylimide in a relatively short time. The results of an experimental study of this thermal reaction in the absence of a catalyst are to be published later.

Assessment of Sylphons Lifetime

2008 ◽  
Vol 59 (5) ◽  
pp. 605-610
Author(s):  
Alexandru Pupazescu ◽  
Stefan Minoiu ◽  
Constantin Manea
Keyword(s):  
Elevated Temperature ◽  
Strain Distribution ◽  
Accurate Determination ◽  
Multiaxial Fatigue ◽  
Tensile Curve

The paper contains an assessment of the sylphons lifetime for multiaxial fatigue. Three criteria were used two based on s � N diagram and one based on energy. For a more accurate determination of the sylphons lifetime the stress and the strain distribution been determined using FEM, the tensile curve of the steel W 4541 at elevated temperature.

Metabolic response to temperature stress in the Colombian freshwater crab Neostrengeria macropa (H. Milne Edwards, 1853) (Decapoda: Brachyura: Pseudothelphusidae)

2021 ◽  
Author(s):  
David M Hudson
Keyword(s):  
Metabolic Response ◽  
Infrastructure Development ◽  
Predator Prey ◽  
Temperature Range ◽  
Indicator Group ◽  
Response To Temperature ◽  
Performance Results ◽  
The City ◽  
The Ideal

Abstract Freshwater crustaceans are distributed throughout the montane and lowland areas of Colombia, and are therefore a useful indicator group for how aquatic species will respond to climate change. As such, metabolic determination of physiological performance was evaluated for the Colombian pseudothelphusid crab, Neostrengeria macropa (H. Milne Edwards, 1853), over a temperature range inclusive of current temperatures and those predicted by future scenarios in the plateau around the city of Bogotá, namely from 8 °C to 30 °C. The performance results mostly aligned with previous exploratory behavioral determination of the ideal temperature range in the same species, although the metabolism increased at the highest temperature treatments, a point when exploratory behavior declined. These results indicate that this species of montane crab behaviorally compensates for increased thermal stress by decreasing its physical activity, which could have negative predator-prey consequences with changes to community structure as different species undergo climate-mediated geographic range shifts in the region. As this species is endemic to the plateau surrounding Bogotá, it also experiences a number of other stressors to its survival, including infrastructure development and invasive species.

Dissociation of imino proton(s) of a highly water-soluble metal-free phthalocyanine and determination of its pKa value in water

2013 ◽  
Vol 17 (06n07) ◽  
pp. 447-453 ◽  
Author(s):  
Hiroaki Isago ◽  
Harumi Fujita
Keyword(s):  
Aqueous Media ◽  
Thermal Reaction ◽  
Water Soluble ◽  
Acid Dissociation ◽  
Acid Dissociation Constant ◽  
Metal Free ◽  
Imino Proton ◽  
Pka Value ◽  
Triton X

Dissociation of imino proton(s) in the cavity of the macrocycle of a highly water-soluble, metal-free phthalocyanine ( H 2( H 4 tsppc ); where H 4 tsppc denotes tetrakis{(2′,6′-dimethyl-4′-sulfonic acid)phenoxy}phthalocyaninate) in ethanolic and aqueous solutions has spectrophotometrically been investigated. The spectral changes associated with reaction with NaOH have been found to involve one-proton transfer process in aqueous media while two-protons process in ethanolic media. The acid-dissociation constant of the first imino proton in water (in the presence of Triton X-100) has been determined to be 12.5 ± 0.2 (as pKa) at 25 °C. The doubly deprotonated species in EtOH has been easily converted to its corresponding cobalt(II) derivative by thermal reaction with anhydrous CoCl 2.

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